Electron tube



Patented July 28, 1942 UNITED STATES PATENT OFFICE ELECTRON TUBE FelixHerriger, Berlin, Germany, assignor to C. Lorenz Aktiengesellschaft,Berlin-Tempelhof, Germany, a company Application March 29, 1940, SerialNo. 326,603 In Germany March 23, 1939 9 Claims. (Cl. Z50-27.5)

Discharge vessels are known whose wall is made of a ferromagneticmaterial. Materials of this kind have the advantage that they are easyto unite with glass and have a relatively small heat conductivity sothat the sealing spot at which glass is sealed to the ferromagneticmaterial is not so highly heated as the middle of the discharge vessel.This use of ferromagnetic materials, however, also involves a drawbackin case the discharge vessel is operated at, high l frequencies. Infact, great hysteresis losses due ode, and the other electrodes, whileoutside a to reversals of the magnetic field can arise in field betweenthis anode and adjacent grounded this case, whereby the output of thedischarge parts is effective. vessel will be reduced to a considerableextent. As stated before, the tubular end portion C of Such problemsarise particularly in the case of the vessel is not coated with materialBy suitdischarge vessels of the external-anode type. able constructionalarrangement it will be pos- These losses may be avoided by means of thesible to withhold field lines` from the uncoated invention describedhereafter. part of the vessel.

The accompanying drawing is a sectional view The metallic coating may beaiiXed either showing a vacuum vessel for electron tubes which beforearranging the head D or may be affixed is intended also to constitutethe anode thereof thereafter. T he latter method will be suitable inwell known manner. if the coating is liable to be affected by the seal-According to the invention the ferromagnetic ing process. material A ofwhich the discharge device is made What is claimed is: n is coattedinsitdealnc outsid with at roi-ferro .25 h 1. An extlelrgalilocelaxpaetlclclarllgea cgevce magne 1c ma eria excep or a u uar en aving a wa or s1 p r o a portion C to which a glass head D is sealed. The materialhaving ferromagnetic DIOpeltieS, Said coating B preferably consists ofcopper, silver, wall portion being provided inside and outside chromiumcr rhodium. The coating within the with a coating of electrically goodconducting vessel must have a vapor pressure small enoughnon-ferromagnetic material, Said Coating eX- not to affect the vacuum toan appreciable detending over. substantially all the surface of saidgree underv operating temperature conditions. felloiailelrlllrmaifrlld.t l 1 Any ofthe well known methods may be employed 1S@ a ge eVlCe aCCOl"me 0 C 31m i for producing the coating B. For instance, this wherein thesaid coating is 0.1 to 2 millimeters may be producedt bg electtrolylssor ,ty lrijlaltirtlgg. mShlCldriesi-a devic c din t la' 1 in In the caseof u eno dea ing wi h ig em- 1SC rge e a cor g o c 1m i peratures it hasbeen found desirable to employ a WhlCh 011 end 0f Seid Wall POIIOII 1S111100315661, coating of copper. For higher temperatures a, arid furthercomprising a glass head sealed to coating of chromium or preferably ofrhodium ths r'lfogh-f manufacturing the bulb por will be suitable. 40

The precaution of arranging such coating on ugr; Ollelredcafngvm;vglecllrlneth all sides has for its object to prevent the elecn. p 0 .gg y c3" indrical envelope of a material having ferrotrcmagnetic fieldfrom entering the ferromagma nemo To ertes Seann la h ad t ne layeraffixed to this material g .p p g a g SS .e o o neue mater 1&1 The th 45end of said envelope, and then applying a coatmust 11e/me be of a'thlckness greater than e ing of non-ferromagnetic material having goodPenetfawn depth 0f the eleiromagneilc fieldeiectric conductivity tosubstantially au of the The penetration depth depends on frequency.inner surface of Said envelope Since, however, in the case of lowfrequencies 5 The method of claim 4,J in which said goatthe arisinglosses are of little consequence these mg of good conductive material isapplied to al1 considerations are only concerned with relatively highfrequencies, such as 108 cycles per second. In this regard thepenetration depth is in the order of magnitude of 2 millimeters or less.

Penetration depth less than 0.1 millimeter need not be considered here.The coating should hence be 0.1 to 2 millimeters in thickness.

The coating itself need not be vacuum-tight and may therefore be acoarse-grained electrolytic precipitate.

It is important that the ferromagnetic body should be provided on allsides with a well conducting coating of non-ferromagnetic material.Within the discharge vessel there is the field between the body socoated, which may be the anthe inner surface of said envelope except inthe immediate vicinity of said glass head seal.

6. The method of claim 4, which includes the additional step of applyinga coating of said non-ferromagnetic material having good electricconductivity to substantially all of the outer surface of said envelope.

7. An electron discharge device including a generally cylindrical wallportion of ferromagnetic material having high electric conductivity pnsubstantially all the inner surface of said wall f'portion, a glass headsealed to one end of said ,fwall portion, and an electrode-supportingmem- 1' ber of insulating material sealed to the other end of said wallportion.

8. An electron discharge device according to claim '7, furthercomprising a coating of nonaeedeev ferromagnetic material having highelectric conductivity on substantially al1 the outer surface of saidwall portion.

9. An electron discharge device according to claim rI, furthercomprising a coating of nonferromagnetic material having high electricalconductivity on substantially all the outer surface of said Wallportion, in which said coating of said non-ferromagnetic materialextends over all of the surface of said ferromagnetic material except tothe immediate vicinity of said glass head.

FELIX HERRIGER.

